Four of the five of the projects are involved in imaging different aspects of cancer metabolism. Each of these projects are using data analysis methods and models developed for the particular tracers, i.e. Fluorodeoxyglucose, glucose, thymidine, and fluoromisonidazole. The non-imaging project is Project 3, which is a modeling and data analysis project entitled Impact of Noise and Heterogeneity on Parameter Estimation. The specific aims (briefly) of Project 3 are: 1) Effect of Noise on Parameter Estimates, 2) Validation of the Mixture Analysis Approach in the Presence of Heterogeneity, 3) Effect of Heterogeneity on Parameter Estimates.